The present invention relates to a word processor with a ruled line display function. Many word processors for inputting and editing a text can rule a line in the text for underlining or making a table when a line ruler mode is selected. Those word processors with a ruled line display function are designed so as to rule a line by following a leading cursor (line pointing cursor) which is movable in a text display screen of the display device. The display screen is designed to display ruled lines and characters separately in their respective regions; that is, there are regions for ruled lines and regions for characters. In general, the display screen is constructed of a gathering of many square or rectangular character regions arranged vertically and horizontally; that is, the screen is divided into rows and columns of character regions in which a letter or a symbol is displayed by selectively lighting a specific group of pixels (picture elements). Furthermore, many word processors have line display regions between the character regions.
Various methods of displaying the leading cursor in the line ruler mode have been proposed. For example, provision is made to display a cursor in the line ruler mode by a reverse display of a whole character region, and another provision is made to display a cursor by a reverse display of not the whole region but only the upper or lower half of a character region. However, a problem arising in the above methods is that the operator cannot see clearly where a line will be drawn at the beginning of ruling a line. More exactly, it is not apparent whether the starting point of a line is at the upper corner of the cursor in a character region or the lower corner thereof, and accordingly a line may be ruled on a different place from where desired.
When a display device of a word processor is small, another problem arises in respect to the line ruling on the display. The printer of the word processor can print various kinds of lines; such as a thin solid line, a thick solid line, a broken line, a chain line, and so on. However, the display screen cannot distinctively show each structure of line, because the allotted line display region is naturally small on the order of one-pixel-width. Therefore these lines are shown by a same solid line on the display and the kind of line selected by the operator for printing is displayed at a corner of the display screen for reference. The problem with such a word processor is that the operator cannot check immediately on the display screen which kind of line will be printed by the printing mechanism and that a different kind of line from the desired one may be mistakenly printed.